(1) Field of the Invention
This invention relates to pipe and fencing and, more particularly, to detectible pipe and electric fencing molded of conductive loaded resin-based materials comprising micron conductive powders, micron conductive fibers, or a combination thereof, substantially homogenized within a base resin when molded. This manufacturing process yields a conductive part or material usable within the EMF, thermal, acoustic, or electronic spectrum(s).
(2) Description of the Prior Art
Pipe is used in many applications for transport of fluids, such as oil or natural gas, or as a protective covering, or conduit, for electrical or telecommunications wiring. In many cases, the pipe is buried for improved safety or appearance. There are circumstances, such as during subsequent construction work, when it is necessary to precisely locate the path of the buried pipe. Location of metal pipes is typically performed using any of a variety of metal detection techniques. However, most buried natural gas pipe is constructed from a non-metal material such as polyvinyl chloride (PVC). Traditional metal detection techniques do not work for PVC pipes. To provide pipe tracing, a copper wire is typically wrapped around the PVC pipe prior to burial. The provision of this locator wire that is detectable by normal methods has at least two disadvantages. First, it is relatively easy for the wire to be broken during installation or during subsequent construction events. If the wire is broken, location techniques may not work properly. Second, the proper installation of the pipe is made more difficult due to the lack of ruggedness of the locator wire. Solving the above issues is an important object of the present invention.
Electric fence is applied mainly as a means to corral domesticated animals. In a typical application, the fence is charged with a relatively large, static voltage. When an animal contacts the fence, the voltage discharges through the animal and into the ground. The discharge shock is unpleasant for the animal but not sufficient to cause injury. The fence typically comprises conductive metal wiring that is run parallel to the ground. The prior art electric fence system has at least two disadvantages. First, depending on the type of metal wire used, corrosion of the wire surface can reduce shock capability or, in the worst case, create a risk of animal injury. Second, wire breakage will typically disable the electric shock function of an entire section of fence. Solving the above issues is an important object of the present invention.
Several prior art inventions relate to detectible or locatable pipe. U.S. Pat. No. 4,947,012 to Minarovic teaches an electro fusion marker which fuses two pipe sections together by means of an integrated heating coil. This invention also teaches that the heating coil, after it is buried, doubles as the inductor to a resonant LC circuit for locating purposes. U.S. Pat. No. 6,305,423 B1 to De Meyer et al teaches a thermoplastic or thermoset pipe that includes a conductive textile reinforcement layer for heating and leak detection purposes. U.S. Pat. No. 5,905,194 to Strong teaches a pipe line design with an integral fault detection method utilizing an inner electrically conductive layer, a layer of dielectric material, and an outer layer of a conductive coaxial element. This invention also teaches the use of time domain reflectometry (TDR) for leak detection which comprises applying a high frequency pulse to one end of the pipe line and measuring the time required for reflections of the pulse to return in order to calculate the location of the leak. In one embodiment, the inner conduit comprises PVC with a metallized outer coating. U.S. Pat. No. 5,177,996 to Sahakian teaches a coaxial liquid leak detection cable that comprises a wire conductor layer, an insulation layer impermeable by water or water vapor, a braided wire conductive layer, a second layer of water and water impermeable insulation, and an outer layer that is braided, woven, or netted in order to allow permeation by liquids. This invention also teaches that the cable be buried next to the pipe line so that any leaks in the line would permeate the cable and allow for TDR to determine its location.
U.S. Pat. No. 5,117,676 to Chang teaches a leak detector for natural gas pipelines comprising a plurality of acoustic microphones arranged along the exterior of the pipeline that are responsive to sounds generated by escaping gases through one or more holes in the pipeline. The outputs of the microphones are then monitored to determine if peaks in the acoustic spectrum occur at a predetermined wavelength of a standing wave of escaping gas. U.S. Patent Publication US 2002/0134448 A1 to Goodman teaches a locatable magnetic polyethylene gas pipe distribution system utilizing the mixing of ferrite particles into the polyethylene resin and magnetizing them during the molding process. This invention also teaches a method of directionally magnetizing the embedded ferrite particles in a distinctive spiral pattern that helps to distinguish it from background magnetic objects. U.S. Pat. No. 5,699,048 to Galloway teaches an omni-directional passive electrical marker for underground use comprising plural tuned circuits allowing for better transmission to the receiver regardless of the markers orientation in the ground. U.S. Pat. No. 6,246,328 B1 to Parkinson et al teaches an extended range passive marker comprising a wire wound planar spiral portion and a wire wound wall portion joined to the wire wound planar spiral portion and extending outward form the circumference. This invention also teaches of a hollow sphere filled with a liquid and a buoyant carrier that encases the circuits of the passive marker allowing it to orient itself for best reception and subsequent transmission underground.
Several prior art inventions relate to electric fences. U.S. Patent Publication US 2003/0066993 A1 to Chamove teaches the use of spots or stripes on an electric fencing tape to add a visual deterrent to the electric fence boundary. U.S. Pat. No. 6,710,253 B2 to Wildschut teaches an electric fence tape, rope or wire that utilizes two conductive elements with different electrical and mechanical properties woven together in a polymer fiber and a braided outer jacket. This invention also teaches the fencing will maintain a conductive ability longer than a fence that only has one conductive element. U.S. Pat. No. 6,519,131 B1 to Beck teaches an electric cattle guard comprising a first layer of non conductive flexible natural or synthetic rubber and a second layer of the same material that has a plurality of electrically conductive particles, fibers or a mixture thereof. This invention also teaches the conductive filler to be either carbon black or graphite or a metal such as aluminum, copper, nickel, tin or stainless steel in either fibers or powders.
U.S. Pat. No. 6,513,793 B2 to Bellon teaches an electric fence that utilizes two conductive elements with different mechanical and electrical properties. The first conductive element that is used has excellent mechanical properties against breakage and corrosion and the second conductive element is highly conductive and covered for most of the distance by a sheath to protect against breakage and corrosion. This invention then teaches that the two conductive elements are joined by a metal connector at intervals along the fencing to insure a strong conductive path. U.S. Pat. No. 6,341,550 B1 to White teaches an electric braided fence that utilizes a non conductive inner core of a high strength synthetic yarn and an outer conductive braided shell of either copper wire or copper coated wire or a copper alloy braided along with a highly visible polyester fiber. U.S. Pat. No. 6,472,602 B1 to Pokrandt teaches an electric fence line that utilizes a woven tape of electrically conductive stainless steel strands and a polyethylene monofilament yarn that run longitudinally along the tape and a stainless steel bonding strand that zigzags across the tape at intervals to insure a strong conductive path along the entire length of the tape. U.S. Pat. No. 5,096,162 to Cleveland teaches an electric fence wire construction that utilizes an elongated plastic strip folded over parallel conductive wires in order to have an electric fence that visually looks like a rail fence system. This invention teaches that the elongated plastic strip has a tooth like pattern on the edge so that the conductive wire element is exposed.